Developing Web Applications with Oracle and XML NYOUG General Meeting March 13, Jason Cohen

Transcription

1 Developing Web Applications with Oracle and XML NYOUG General Meeting March 13, 2001 Jason Cohen

2 What is XML? Oracle and XML XSU SNC and XML Tuning XML Intermedia Text Issues How to get more info. Agenda

3 What Is XML A universal standard for electronic data interchange. XML is a markup language for documents containing structured information. XML provides a facility to define tags and the structural relationships between them. A sequence of text characters that encodes data using tags. DTD, Schemas, define the legal names for the tags in a particular XML vocabulary (i.e. fpml)

4 XML AN EXAMPLE <?xml version="1.0"?> XML Identifier <EMPLIST> Start Tag <EMP> Node Element <EMPNO>7654</EMPNO> <ENAME>MARTIN</ENAME> </EMP> <EMP> <EMPNO>7788</EMPNO> <ENAME>SCOTT</ENAME> </EMP> </EMPLIST> End Tag

5 Why XML? Vendor, platform, language neutral technology for web-based data exchange. XML was created so that richly structured documents could be used over the web. HTML, comes bound with a set of semantics and does not provide arbitrary structure. Simplifies the task of connecting applications and services over the web. Looks good on a resume.

6 Oracle 8i Platform for XML

7 Oracle 8i Platform for XML XDK XML parser for PL/SQL,java,c,c++ XSLT processor for java XML schema processor for java XML Transviewer beans XSQL Servlet XSU Conforms to XML 1.0 standard.

8 XDK Supports both DOM/SAX Interfaces. Supports XML Namespaces. Integrated XSLT 1.0 support. Schema support is early release. Build graphical apps with Transviewer beans. XML Class generator is beta.

9 Oracle 8i Platform for XML Helper packages (xpath, xml, etc.) Developed by oracle XML development team. Uses PL/SQL parser. Reduces coding time. Download from O reilly site. Ftp://ftp.oreilly.Com/pub/examples/oracle/or xmlapp/

10 XSQL Servlet Engine

11 XSQL Servlet Engine Requires configuration file containing connection info. Requires.xsql file to be passed to the servlet engine. HTTP Request: XSQL File to process HTTP request: <?xml version="1.0"?> <xsql:query connection="demo" xmlns:xsql="urn:oracle-xsql"> SELECT EMP_FNAME, EMP_LNAME, TITLE FROM EMPLOYEE E WHERE E.DEPT = '{@dept} </xsql:query>

12 . XSU XML SQL Utility

13 XSU - Cont. Core Java class libraries for automatically and dynamically rendering the results of arbitrary SQL queries into canonical XML. Contains PL/SQL wrappers for most of the classes. Installed into SYS account. Native with and higher. Uses column names or alias as tags. XMLGEN or DBMS_XMLQUERY? Use LOADJAVA utility to load XSU classes.

14 XSU Sample Code SELECT source as party, text, transitionumber FROM org_table WHERE org_id = ORGWILL ; ORG_TABLE ORG_ID SOURCE TEXT TRANSITION_NUMBER setrowtag( conversation ); setrowsettag( conversations ); uselowercasetagnames(); seterrortag( Error ); setrowidcolumn( ORG_ID'); <?xml version = '1.0'?> <conversations> <conversation num= ORGWILL"> <party>jason Cohen</party> <text>hello...</text> <TransitionNumber>3</TransitionNumber> </conversation> </conversations>

15 Tuning XML Use bind variables instead of string concatenation. Xmlgen.setBindValue( emp_id', emp_id); SelectString := 'SELECT * FROM employee WHERE id = :emp_id ' ; Xml_clob := Xmlgen.getXML(SelectString,0);

16 Tuning XML Use generic insert for bulk inserts. Requires about 50mb for java_pool_size for install of JVM. Uses around 10mb of java pool. Use Intermedia text for searching large XML objects. Use SAX API instead of DOM when processing structured data. SAX, the simple API for XML, is a standard interface for event-based XML parsing

17 Intermedia Text Enables text-pattern searching within XML documents. Creates special indexes on XML tags being searched. Must update index to include new rows. CTXSRV to rebuild indexes.

18 Intermedia Text Similar to XPATH expressions. Limited attribute value searching functionality. When InterMedia indexes exist on a table the cost-based optimizer is always used.

19 Intermedia Text - Examples A) SELECT id FROM employee WHERE dept = MARKETING' and contains (details, 'BOB WITHIN emp_fname ) > 0 B) SELECT ID FROM employee_relocation WHERE dept = MARKETING and ( contains (source, '(DESKA WITHIN desk) and (USRA WITHIN user)') > 0 OR contains (destination,'(deska WITHIN desk) and (USRA WITHIN user)') > 0 ) and ( contains (source, 'DESKA WITHIN desk') > 0 OR contains (destination, 'DESKA WITHIN desk') > 0 );

20 Issues XSU is separate install with or lower. Need to upgrade to for large XML result sets due to bug with dbms_lob.append failing with an ORA-600. SelectNodes() bug failing with an ORA No PL/SQL interface to SAX. Must use JAVA, C, or C++.

21 Issues Treats XML stored in a column as string not as XML. Slow on inserts (1000 inserts > 20 sec). Older versions of OO4O didn t support temp lob s. XML Query is only working draft. XML PL/SQL PARSER CRASH

22 Oracle 9i XML Features XDK is built in. XML-based messaging with Advanced Queuing. New XML type.

23 Summary XML is a vendor,platform,language neutral technology for data exchange over the web. Use Oracle s XDK for developing XML applications Use XSU to transform SQL queries into XML. Use XSQL to submit HTTP request from a browser. Intermedia Text for fast searching within XML documents.

24 Where to Get More Information XML discussion group at: ns.htm Building Oracle XML Applications, by Steve Muench.